There is a need for high strength, tamper resistant packaging materials for many applications including, for example, pet food, bird seed, grains, controlled environment feeding (e.g., in test laboratories), livestock feed, and so on.
It is known to use woven materials, for example, woven polymeric materials (i.e., polymeric filaments that are woven into a mesh), to impart strength to packaging materials. Such woven materials are typically used in combination with other materials to provide the desired degree of impermeability, strength, stiffness, and other attributes. However, such materials may be difficult to join to other materials and present numerous challenges when being formed into a package.
For example, in traditional packaging formation, the ends of two panels or faces of a tubular structure are typically brought together and joined via adhesive, heat sealing, or otherwise to form a pinch seal. However, in many instances, in particular where a woven polymer layer is used, the area to be joined is quite thick, and therefore, difficult to join without using relatively thick heat seal layers (or a relatively high amount of adhesive material), which, in some instances, may require high heat sealing temperatures. Unfortunately, the application of too much heat can cause the woven polymer to soften and/or distort, thereby compromising the integrity of the structure. Additionally, even where a pinch seal is successfully formed, the seal often tends to be weak, and may fail when the package is being filled. As a result, packages using woven polymer materials are typically sewn or stitched and/or taped at one or both ends to reinforce the seal. However, this process is complicated and costly. Additionally, such processes are prone to issues caused by needle breakage, which may result in contamination of the product with broken needles or needle shards.
To overcome these obstacles, it has been proposed to “step cut” one panel or face of the package (such that one panel or face is longer than the other), and simply fold the longer panel over the shorter panel, as disclosed in U.S. Pat. No. 6,800,051. This generally reduces the thickness of the overlapping areas to be sealed. However, woven materials are generally difficult to cut in this manner without unraveling and forming strings that cause other processing issues.
Thus, there is a need for high strength packaging materials including woven polymeric materials that are capable of being formed into packages. There is also a need for a method of forming a package including woven materials in which a sufficiently strong heat seal can be formed without the need for sewing.